I remember a recommendation for phono cable burn in using the signal of a cd player or tuner, connecting the phono cable with arm to the outputs of the tuner.
I think I remember having read to connect the pins at the cartridge end of the arm.
Your comments, gentlemen?
The LOMC cartridge has an inductance which is in parallel with a capacitance of the tonearm cable. An inductance in parallel with a capacitance is how radios tune stations...
This creates a high Q electrical resonance, usually between 100KHz and 5MHz.
It can go into excitation, activated by the energy of the cartridge despite not being anywhere near the same frequency.
Because of the high Q nature of the resonance, it can be as much as a 30dB peak!
This RFI is injected directly into the input of a phono section. If the phono section isn't designed to deal with this, it can distort and thus not sound right (usually bright). This is why 'cartridge loading' resistors are sometimes used (for phono sections where the designer did not take this phenomena into account) which have the effect of detuning the resonance, thus killing the RFI.
SUTs cannot pass frequencies this high and so block the RFI. For those phono sections that have this issue, the SUT will thus sound better.
super explained, in addition, certain cantilever materials + stylus also have resonance .
exsampe emt tsd 15 adds a calculated capacitor to smooth them out no treble rise or resonance these can even be in the low range 15kh-70khz.
Unfortunately, not every manufacturer eliminates this resonance.
after then absolutely straight frequency response in the audible range. Sorry for offtopic
super explained, in addition, certain cantilever materials + stylus also have resonance .
exsampe emt tsd 15 adds a calculated capacitor to smooth them out no treble rise or resonance these can even be in the low range 15kh-70khz.
Unfortunately, not every manufacturer eliminates this resonance.
after then absolutely straight frequency response in the audible range. Sorry for offtopic
And mechanical resonance too. here are measurements of different cantilever materials and their mass and the resulting resonance frequency.from experience i can say that the boron cantilever +shibata stylus produces the most amazing treble. clean sweet perfect
Hi All, I am thinking of making a pair of phono cables out of Gotham 11301 cable. I understand from forum discussions that it is better to use cables with lower capacitance, but they usually only quote one capacitance figure.
The following are capacitance figures for the 11301. So, which figure should I go by? Would the 11301 be a good choice for phono cable?
Hi Solypsa, actually I will be using the phono cable in two situations; 1, tonearm to a built in SUT in a LCR phono, and 2, tonearm directly into the active gain stage of the Aesthetix Io. Would the Gotham GAC4 be better in one arrangement over the other?
I have no technical knowledge, but my gut feeling is that for phono cable, symmetrical cable is better. Any truth in this ?
You are correct. The capacitance should be 30pf/foot or less, so you can have 100pf or less for the total length. This is particularly important for MM cartridges where the inductance is higher, associated with the higher output.
For LOMC cartridges its still important because the capacitance is in parallel with the inductance of the cartridge, forming an electrical resonance that can be anywhere from 100KHz to 5MHz. when this resonance goes into excitation, Radio Frequency Interference is thus generated and injected directly into the input of the phono preamp. The higher the frequency the greater the possibility that the phono preamp's input can reject it. Many phono section designers seem to ignore or are ignorant of this phenomena; their products thus require a 'cartridge loading' resistor at their inputs, but as you can see now the resistor is really for the benefit of the phono section as it detunes that resonance, and in so doing prevents the RFI.
super explained, in addition, certain cantilever materials + stylus also have resonance .
exsampe emt tsd 15 adds a calculated capacitor to smooth them out no treble rise or resonance these can even be in the low range 15kh-70khz.
Unfortunately, not every manufacturer eliminates this resonance.
after then absolutely straight frequency response in the audible range. Sorry for offtopic View attachment 99135
Very interesting info. That looks like an older cartridge. I would recommend replacing this capacitor with something from current production. The older type of ceramic capacitors is really non-linear. My recommendation is C0G/NP0 dielectric from a reputable manufacturer like Vishay, Kemet, or others.
You are correct. The capacitance should be 30pf/foot or less, so you can have 100pf or less for the total length. This is particularly important for MM cartridges where the inductance is higher, associated with the higher output.
For LOMC cartridges its still important because the capacitance is in parallel with the inductance of the cartridge, forming an electrical resonance that can be anywhere from 100KHz to 5MHz. when this resonance goes into excitation, Radio Frequency Interference is thus generated and injected directly into the input of the phono preamp. The higher the frequency the greater the possibility that the phono preamp's input can reject it. Many phono section designers seem to ignore or are ignorant of this phenomena; their products thus require a 'cartridge loading' resistor at their inputs, but as you can see now the resistor is really for the benefit of the phono section as it detunes that resonance, and in so doing prevents the RFI.
Hi Ralph, so what is the maximum capacitance you think is acceptable for a phono cable (the whole cable, no matter what length), specifically a RCA terminated one for MC cartridges if it makes a difference ?
I have posted the capacitance measurements of a Gotham cable above, but they have listed 4 different capacitance measurements, so which figure should I go by?
Hi Ralph, so what is the maximum capacitance you think is acceptable for a phono cable (the whole cable, no matter what length), specifically a RCA terminated one for MC cartridges if it makes a difference ?
Cardas does a lot good phono cables, internal wiring tonearms and phono to preamp.very good sound never felt as limiting. copper cable low capacitance.
Cardas does a lot good phono cables, internal wiring tonearms and phono to preamp.very good sound never felt as limiting. copper cable low capacitance.
quartzacoustic.com
